<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{
            opacity: 0.2;
        }
        .father{
            background-color: pink;
            border: 3px solid red;
            overflow: hidden;
        }
        .son{
            /*浮动*/
            float: left;
            height: 100px;
            background-color: orange;
        }
    </style>
</head>
<body>
<div class="father">
    <div class="son">
        d5rc6vt7by8nu9io
    </div>
</div>
</body>
</html>